Sound-reproducing machine.



) P. .l. PACKMAN.

SOUND REPRODUCING MACHINE- APPLICATION FILED ocT.14. 1910.

1,250,637. Patented Dec. 18,1917.

UNI ED STATES PATENT OFFICE.

PERCIVAL JAMES PACKMAN, F HIGHBURY, LONDON, ENGLAND, ASSIGNOR, BY MESNEASSIGNMENTS, TO THE AEOLIAN COMPANY, OF MERIDEN, CONNECTICUT, A COR-PO-RATION or CONNECTICUT.

Specification of Letters Patent.

SOUND-REPRODUCING MACHINE.

Patented Dec. 18, 1917.

Application filed October 14, 1910. Serial No. 586,985.

To all whom it may concern:

Be it known that I, PERCIVAL J AMES PACK- MAN, a subject of the King ofGreat Britain and. Ireland, residingat 66 Hamilton road, Highbury, inthe county of London, England, have invented certain new and usefulImprovements Relating to Sound-Reproducing Machines, of which thefollowing is a specification.

This inventlon relates to sound reproducing machines in which hill anddale cut records are employed and has for its object to increase thecapacity of a record without substantially diminishing the volume ofsound.

It has been usual to cut a recordof the hill and dale type with thegroove in the form of a U in cross section wh1ch.has'neces-- sitated theuse of a reproducing stylus terminating in a small ball.

Owing to. theU form of the groove, it is not possible to obtain a verylong record on the usual size of blank, as the convolutions of thespiral cannot be brought very close together and be cut to the requireddepth to give a good volume of sound owing to the risk of theconvolutions overlapping one another to some extent.

According to the invention I cut a hill and dale groove of substantiallya V shape in section and I employ a very fine or needle pointed stylusfor the reproduction by contact of its extremity with the bottom of theV shaped groove. It will be understood that contrary to what is the casewith a record formed by a U-shaped cutting instrument,

there is a definite and distinct line of track, that is, the bottom ofthegrooye cut by the point of the instrument, which always coincideswith the true convolutions of the s iral or helix, and against which thepoint 0 the In the drawings, Figure 1 shows diagram-' matically on amuch enlarged scale by way of example a cutter of sapphire or other suitable substance for cutting the V on the record. The angle between thecutting edges is acute, andthe cutting faces or edgesare ground so as toleave a sharp point; will actually yield a very narrow space? the bottomof the groove against which the extremity of the fine or needle pointedreproducing stylus may contact.

The stylus used in carrying out this invention has a hard, fine orneedle point, and is preferably made. of the highest grade hardened toolsteel.

Figs. 2 to 6 show modified forms of tools adapted to be employed forcutting the V- shaped groove in a record. The tools are drawn to a largescale for the sake of clearness.

Fig. shows a greatly enlarged plan view of a small portion of a trackmade according to this invention, showing the'distinct line of trackproduced by the cutting of the groove and a Fig. 8 shows a cross sectionof the same on the line AB of Fig. 7

Fig.9 shows diagrammatically to an enlarged scale a reproducing stylusin position with its fine or needle point in the bottom of the V shapedgroove of a record.

The stem of the stylus is provided of ample thickness with its extremityonly reduced to a fine point so that it may fundamentally bear on theline of track at the bottom of the groove formed by the use of a cuttingtool such as illustrated in F igs. l to 6.

Byv uch means it is possibleto secure reproduction of a hill and dale Vout record without involving any substantial diminution in the Volume ofthe sound, while, furthermore, it is possible to cut arelatively greatnumber of threads or inch and thus to mcrease the capacity of the recordwhile maintaining fullness and .purity of tone without echo. It willthus be understood that the grooves cut will have? a minute width andtherefore also a minute depth, and that by reason of the recording toolactin as a cutter the walls of the groove will e sharply and cleanly cutand by reason of the cutter having a sharp point a smooth and continuousline will be cut at the bottom of the groove. 1

The stylus is conveniently mounted in a h d r so that its mo em nt dueto the tical undulations of the line of track are directly communicatedto the diaphragm in the usual manner. I

What I claim as my invention and desire 5 to secure by Letters Patent isIn a sound-reproducing machine, the combination of a hill and dalerecord having a groove of V-shaped section with a definite line of trackat the bottom; and a stylus having a needle point of narrower ll-shapedsec- 1c tion bearing fundamentally on said line of track.

In testimony whereof, I afiix my signa-' ture, in presence of twoWitnesses. v

PERCIVAL J AMES PACKMAN. Witnesses:

A. BRowNE, L. SIMMONDS.

